1. Field of the Invention
The present invention relates to diorganotellurium(II) compounds and complexes. More particularly, it relates to diorganotellurium(II) compounds wherein the organic radical contains silicon. The described diorganotellurides and transition metal coordination complexes incorporating these diorganotellurides as ligands are soluble in nonpolar organic solvents, making them particularly useful in various catalytic processes including catalytic imaging processes.
2. Description Relative to the Prior Art
Diorganotellurium compounds are well-known in the art. Organic radicals which are bonded to a tellurium(II) or a tellurium(IV) atom can take a wide variety of forms. For example, diorganotellurium dihalides and dicarboxylates are known. (See K. J. Irgolic, The Organic Chemistry of Tellurium, Gordon and Breach Science, Publ., London, 1974.) These diorganotellurium compounds have been found to be useful as oxidants in tellurium physical development processes. It is also known that certain diorganotellurium compounds can function as ligands for certain transition metal compounds. For example, complexes such as Cu.sub.2 Br.sub.2 [Te(C.sub.6 H.sub.5).sub.2 ].sub.4, CuI[Te(p-MeC.sub.6 H.sub.4).sub.2 ] and the like are known. These prior-art complexes have no significant nonpolar organic solvent solubility. This is unfortunate because solubility in these solvents would offer many advantages where the complex is used as the oxidant in an image-forming combination or is part of the light-sensitive component in a photographic element.
Certain silicon-containing moieties can impart nonpolar organic solvent solubility to certain organometallic compounds. This is taught, for example, by Collier et al, U.S. Pat. No. 3,763,197. Thus, compounds such as Ti--CH.sub.2 Si(CH.sub.3).sub.3 ].sub.4 and the like are known to have useful nonpolar organic solvent solubility. While it may appear desirable to form similar tellurium compounds, difficulties would be encountered if this were attempted. Known organometallic compounds having these silicon-containing moieties are made using a conventional salt-elimination reaction, i.e., using a Grignard reagent. If a similar preparation were attempted with tellurium as the metal, only the tellurium(IV) compound would be produced, e.g., Te--CH.sub.2 Si(CH.sub.3).sub.3 ].sub.2 Cl.sub.2. The prior art suggests no method of making stable, nonpolar, organic solvent-soluble tellurium(II) compounds with these silicon-containing moieties.